Abstract: A single use syringe (10) has an outer barrel (11) and an inner barrel (12) slidable within the outer barrel. The two barrels are initially latched together to prevent relative movement therebetween whereby the syringe is in a useable condition. A needle (16) is in fluid communication with the inner barrel and projects initially from a first end of the outer barrel. A plunger (21) in the inner barrel is connected to a plunger actuating rod (22) which extends out the other end of the outer barrel. On first depression of the plunger actuating rod a limit catch (23) prevents full depression thereof but allows sufficient depression to draw fluid into the inner barrel. On the second depression the fluid is ejected and the plunger actuating rod and plunger are allowed full travel whereby latching between the two barrels is disengaged. It is not possible to re-latch the barrels together in the useable condition and therefore further use of the syringe is not possible.